Venereal disease research laboratory (VDRL) test. The VDRL test checks for an antibody that can be
produced in people who have syphilis. This antibody is not produced as a
reaction to the syphilis bacteria specifically, so this test is sometimes not
accurate. The VDRL test may be done on a sample of blood or
spinal fluid. The VDRL test is not very useful for
detecting syphilis in very early or advanced stages.

Enzyme immunoassay (EIA) test. This is a newer blood test that checks for antibodies to the
bacteria that cause syphilis. A positive EIA test should be confirmed with
either the VDRL or RPR tests.

Tests used to diagnose syphilis include:

Fluorescent treponemal antibody absorption (FTA-ABS) test. The FTA-ABS test checks for antibodies to the
bacteria that cause syphilis and can be used to detect syphilis except during
the first 3 to 4 weeks after exposure to syphilis bacteria. The test can be done on a
sample of blood or spinal fluid.

Treponema pallidum particle agglutination assay (TPPA). The TPPA test is used to confirm a
syphilis infection after another method tests positive for the syphilis
bacteria. This test detects antibodies to the bacteria that cause syphilis. This test is not done on spinal fluid.

Darkfield microscopy. This test uses a special microscope to
examine a sample of fluid or tissue from an open sore (chancre) for the
syphilis bacteria. This test is used mainly to diagnose syphilis
in an early stage.

Microhemagglutination assay (MHA-TP). The MHA-TP is used to confirm a syphilis infection after
another method tests positive for the syphilis bacteria.

Why It Is Done

A syphilis infection can spread through the bloodstream to all
parts of the body. If not treated, syphilis can cause severe heart disease,
brain damage, spinal cord damage, blindness, and death.

A test for syphilis is done to:

Screen for syphilis or check treatment for a
syphilis infection. Screening tests help your doctor look for a certain disease
or condition before any symptoms appear. This increases the chance of finding
the infection when it can be cured or treated to avoid long-term problems.

Some states require the VDRL screening test
before a couple can obtain a marriage license.

The Centers for
Disease Control and Prevention (CDC) and the U.S. Preventive Services Task
Force (USPSTF) recommend that all pregnant women be screened
for syphilis early in pregnancy.1, 2

Confirm that a syphilis infection is
present.

Screening for
syphilis and other sexually transmitted infections (STIs) is often done for
people who engage in
high-risk sexual behavior. If you have syphilis, your
sex partner or partners should be notified, tested, and treated to prevent
serious complications and to stop the spread of the disease.

How To Prepare

Are allergic to any
medicines, especially antibiotics, or medicine used to numb the skin
(anesthetics).

Have had bleeding problems or take blood-thinners,
such as aspirin or warfarin (Coumadin).

Are or might be
pregnant.

If you have syphilis, do not have sex until
the test results show you are no longer infected or until you and your sex
partner or partners have completed treatment and the infection has been cured.
Your sex partners should be tested as well.

If you think you might have syphilis, do not
have sex until testing shows that you are not infected.

Talk to your doctor about any concerns you have
regarding the need for the test, its risks, how it will be done, or what the
results may mean. To help you understand the importance of this test, fill
out the
medical test information form(What is a PDF document?).

How It Is Done

A syphilis test may be done on a sample of blood, sore, skin, or
spinal fluid, depending on which type of test is done.

Blood sample

The health professional taking a sample of your blood
will:

Wrap an elastic band around your upper arm to stop the flow of
blood. This makes the veins below the band larger so it is easier to put a
needle into the vein.

Clean the needle site with alcohol. Put the
needle into the vein. More than one needle stick may be needed.

Attach a tube to the needle to fill it with blood. Remove the band
from your arm when enough blood is collected.

Put a gauze pad or
cotton ball over the needle site as the needle is removed.

Put
pressure on the site and then put on a bandage.

Sore or skin sample

A sample of fluid or tissue may be taken from an open sore
(chancre) or from a rash that might be caused by syphilis.

A fluid sample is obtained by gently pressing
the chancre.

Skin or
mucous membrane samples may be obtained by gently
rubbing a cotton-tipped swab over the area affected.

Fluid from a sore
that may be caused by syphilis sometimes is collected and examined with a
special type of microscope (darkfield microscope).

Spinal fluid sample

A spinal tap (lumbar puncture) is done to collect a
spinal fluid sample for syphilis testing.

For a lumbar puncture, a thin needle is inserted into the spinal
canal in the lower back area. After the needle is in place, a small amount of
cerebrospinal fluid (CSF) is removed from the spinal canal. To learn more, see the topic
Lumbar Puncture.

How It Feels

Blood sample

The blood sample is taken from a vein in your arm. An elastic
band is wrapped around your upper arm. It may feel tight. You may feel nothing
at all from the needle, or you may feel a quick sting or pinch.

Sore or skin sample

You may have some discomfort when fluid is collected from an open
sore (chancre). But chancres usually are not very tender or painful.

Spinal fluid sample

You may have some discomfort during a lumbar puncture to collect
spinal fluid for syphilis testing. To learn more, see the topic
Lumbar Puncture.

Risks

Blood sample

There is very little chance of a problem from having a blood sample
taken from a vein.

You may get a small bruise at the site. You
can lower the chance of bruising by keeping pressure on the site for several
minutes.

In rare cases, the vein may become swollen after the blood
sample is taken. This problem is called phlebitis. A warm compress can be used
several times a day to treat this.

Ongoing bleeding can be a
problem for people who have bleeding disorders. Aspirin, warfarin (Coumadin), and
other blood-thinning medicines can make bleeding more likely. If you have
bleeding or clotting problems, or if you take blood-thinning medicine, tell
your doctor before your blood sample is taken.

Sore or skin sample

There is very little risk of complications from having a sample
taken from an open sore (chancre), skin rash, or mucous membrane.

Spinal fluid sample

There is little risk associated with having a lumbar puncture to
obtain a spinal fluid sample for syphilis testing. To learn more, see
the topic
Lumbar Puncture.

Results

Syphilis tests detect
antibodies in blood or body fluid or tissue to the
bacterium that causes syphilis (Treponema pallidum).
Results are usually available in 7 to 10 days.

Darkfield microscopic examination

Normal:

No syphilis bacteria are seen.

Abnormal:

Syphilis bacteria are seen.

Syphilis tests of blood and spinal fluid

Normal:

No antibodies to syphilis are present. This is called a
nonreactive or negative result.

Abnormal:

Antibodies to syphilis bacteria are present. This is called a
reactive or positive test.

A result that is not clearly normal or abnormal is called
inconclusive or equivocal.

The antibody to the syphilis bacteria (reagin) is not
present. This is called a nonreactive or negative result.

Abnormal:

The antibody reagin is present. This is called a reactive or
positive test.

The accuracy of testing often depends on the
stage of syphilis. Syphilis testing may need to be repeated if initial results
are uncertain or if you have had repeated exposure to syphilis, such as from
repeated unprotected intercourse.

What Affects the Test

Reasons you may not be able to have the test or why the results may
not be helpful include:

The use of antibiotics before having the
test.

A blood transfusion in the weeks before having the
test.

Having other conditions or diseases, such as
lupus,
liver disease,
HIV infection, or
a tropical bacterial infection called yaws.

What To Think About

Most states require doctors to report all cases of
syphilis to the local health department. In some states, doctors
are also required to ask for the names and addresses of your recent sex
partners. If you have syphilis, the health department may contact you to make sure
that you get treatment. If you give the names of your sex partners to your
doctor or the health department, they will be contacted in confidence by the
health department and advised to have a test for syphilis.

About results

If a screening test is positive (reactive), the
strength of the result may be determined by measuring the amount of reagin. The
results are then given in titers.

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How this information was developed to help you make better health decisions.